Dry reforming of ethane over titania-based catalysts for higher selectivity and conversion to syngas

Ethane, one of the key components of shale gas, is a valuable feedstock for the production of syngas (CO + H₂) via the C[sbnd]C bond cleavage during dry reforming of ethane (DRE) reaction. Selective catalysts are needed to direct this reaction pathway against the competing C[sbnd]H bond cleavage for ethylene formation. In this study, Fe, V and Rh oxides supported on TiO₂ catalysts were prepared by impregnation method. The catalysts were tested for DRE with the main target of enhancing selectivity to syngas (CO and H₂) and reducing byproducts (methane and ethylene) formation. The catalysts were characterized using X-ray diffraction, scanning electron microscopy, NH₃/CO₂ temperature programmed desorption and H₂-temperature programmed reduction. Temperature programmed oxidation was utilized to characterize the coke contents of the spent catalysts. The catalysts were evaluated for DRE reaction in a fixed-bed reactor at the temperature range from 500 °C to 650 °C and CO₂/ethane ratio from 2:1 to 10:1 (mol/mol). It was found that ethane conversion over the three catalysts increased in the order Rh/TiO₂ > Fe/TiO₂ > V/TiO₂. Rh/TiO₂ catalyst exhibited > 99 % ethane conversion, 36 % and 61 % yields of H₂ and CO, respectively, at 650 °C and CO₂/ethane ratio of 5.0. The high conversion of ethane was mainly attributed to the enhanced dispersion of Rh oxides on the TiO₂ support coupled with the balanced surface acidic and basic sites. The Rh catalyst facilitated C[sbnd]C bond dissociation of ethane thereby forming methyl intermediates which then reacted with adsorbed CO₂, thereby enhancing higher syngas production during DRE reaction.